LONDON (Reuters) – British Foreign Secretary Boris Johnson is expected to travel to Tehran this weekend in a bid to win the release of a jailed Iranian-British aid worker, the Guardian newspaper reported on Thursday.

Britain’s Foreign Secretary Boris Johnson gives a speech at the Foreign Office in London December 7, 2017. REUTERS/Victoria Jones/Pool

Nazanin Zaghari-Ratcliffe, a project manager with the Thomson Reuters Foundation, was sentenced to five years in jail after being convicted by an Iranian court of plotting to overthrow the clerical establishment. She denies the charges.

Zaghari-Ratcliffe’s fate become a major political issue in Britain after Johnson made remarks on Nov. 1 that appeared to cast doubt on statements from her employer about what she had been doing in Iran.

The Thomson Reuters Foundation, a charity organisation that is independent of Thomson Reuters and operates independently of Reuters News, said she had been on holiday.